It sounds like you are loosing power to the ignition occasionally. I had a similar problem once with a 64 Dodge station wagon. It turned out to be the ignition switch. Try lightly jiggling the key while you are driving down the road and see if it causes the problem. Turn it back and forth slightly but not far enough to switch it off or turn the starter. You could have a loose conection in the circuit to the coil, which would include the resister, or the orange box could be going after all these years.